Dry etcher apparatus for preventing residual reaction gas from condensing on wafers after etching

ABSTRACT

A dry etcher for etching a thin film on a wafer, includes an etching chamber having the wafer loaded therein and a supply system for supplying a reaction gas to the etching chamber to etch the thin film on the wafer. A loadlock chamber controls an etching atmosphere before and after the wafer is loaded in and unloaded from the etching chamber. A pumping device pumps the reaction gas out of the etching chamber and the loadlock chamber after the thin film is etched. A heater or cleaning device prevents any residual reaction gas remaining in the etching chamber and loadlock chamber from condensing on the wafer when the wafer is exposed to ambient atmosphere after exiting the loadlock chamber. The heater or cleaning device may be disposed in the etching chamber or the loadlock chamber.

FIELD OF THE INVENTION

The present invention relates to a dry etcher for etching semiconductordevices, and more particularly, to a dry etcher and method of preventingthe reaction gas remaining on a wafer after the wafer is etched frombeing condensed on the wafer, without having to resort to a separatedevice or a separate treatment method.

BACKGROUND OF THE INVENTION

An etcher is an apparatus used in manufacturing semiconductor devices,which, according to the object of the process, selectively eliminatesvarious thin films such as silicon film, polysilicon film, and siliconoxide film, formed under a photoresist film. The etching may beclassified as wet etching using chemicals or dry etching using gas. Theetcher apparatus would thus be referred to as a wet etcher or a dryetcher.

FIG. 1 schematically shows the construction of a conventional dryetcher. Referring to FIG. 1, the conventional dry etcher includes awafer carrier 4, an etching chamber 5, loadlock chambers 6, and a gasdischarger 7.

The wafer carrier 4 loads wafers 2 from a wafer cassette 1 and carriesthe wafers 2 via a conveyer 3 into the loadlock chamber 6. A reactiongas is input into the etching chamber 5, in which a high degree ofvacuum is maintained. The loadlock chambers 6 are interconnected to theetching chamber 5 through entrances 5a and 5b. The loadlock chambers 6are at approximately the same environment as that in the etching chamber5.

The gas discharger 7 pumps/purges out the reaction gas remaining in theloadlock chamber 6 and etching chamber 5 after the etching process iscompleted, so as to maintain the high degree of vacuum in the loadlockchamber 6 and etching chamber 5.

When etching polysilicon films and the like by means of the dry etcheras described above, Cl₂, HBr, or the like is usually used as thereaction gas. Such gases exhibit a strong tendency to condense when theyare exposed to an atmospheric state. Although, the gas discharger 7seeks to pump/purge out the reaction gas remaining in the loadlockchamber 6 and etching chamber 5 after the etching process, some portionof the reaction gas still remains that is condensed and liquified on thewafers. The wafers containing the liquified gas are then subjected tothe succeeding manufacturing process.

However, such condensed and liquified gas on the wafers must beeliminated because it can degrade the quality of the semiconductor aswell as cause downstream manufacturing process problems. Generally, aseparate device or a separate process is employed to eliminate thecondensed and liquified gas. Such separate devices or processes,however, cause delays in the manufacturing process and increase the costof manufacturing a semiconductor device.

In light of the foregoing, there exists a need for an etcher and methodof preventing gas remaining on a wafer after the wafer is etched frombeing condensed on the wafer, without having to resort to a separatedevice or a separate treatment method.

SUMMARY OF THE INVENTION

The present invention overcomes one or more of the above describedproblems of the prior art. Accordingly, it is an object of the presentinvention to provide a dry etcher that prevents the reaction gasremaining on a wafer after the etching process from condensing on thewafer, without having to employ a separate device or a separatetreatment method.

It is another object of the present invention to provide a method fordry etching a wafer, which prevents the reaction gas remaining on awafer after the etching process from condensing on the wafer, withouthaving to employ a separate device or a separate treatment method.

To achieve these and other objects, the dry etcher of the presentinvention comprises an etching chamber, a loadlock chamber, and a meansfor preventing residual reaction gas from being condensed on the wafer.More specifically, the dry etcher comprises an etching chamber having awafer loaded therein; a supply means for supplying a reaction gas to theetching chamber to etch a thin film on the wafer; a loadlock chamber forcontrolling an etching atmosphere before and after the wafer is loadedin and unloaded from the etching chamber; means for pumping the reactiongas out of the etching chamber and the loadlock chamber after the thinfilm is etched; and means for preventing any residual reaction gasremaining in the etching chamber and loadlock chamber from beingcondensed on the wafer when the wafer is exposed to ambient atmosphereafter exiting the loadlock chamber.

Preferably, the means for preventing any residual reaction gas frombeing condensed is a heater or a cleaner disposed in the etching chamberor the loadlock chamber. This residual reaction gas remaining on thewafer is then pumped out of the etching chamber and the loadlockchamber.

In another aspect, there is provided a dry etching method for preventingresidual reaction gas from condensing on a wafer etched by a dry etcher,the dry etcher having an etching chamber and a loadlock chamber, themethod comprising the steps of: (a) loading a wafer in the etchingchamber; (b) supplying a reaction gas into the etching chamber whilemaintaining a high degree of vacuum in the etching chamber and theloadlock chamber; (c) etching the wafer in the etching chamber; (d)discharging the reaction gas out of the etching chamber and the loadlockchamber; and (e) heating a residual reaction gas simultaneously withstep (d) so as to activate any residual reaction gas remaining on thewafer after the wafer is etched, thereby preventing the residualreaction gas from condensing on the wafer when exposed to an ambientatmosphere when the wafer is unloaded from the loadlock chamber afterbeing etched.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, and other features and advantages of the presentinvention will become more apparent by describing in detail preferredembodiments thereof with reference to the attached drawings, in which:

FIG. 1 is a schematic constructional view of a conventional dry etcher;

FIG. 2 is a schematic constructional view of a dry etcher foreliminating residual reaction gas remaining on a wafer according to afirst embodiment of the present invention;

FIG. 3 is a schematic constructional view of a dry etcher foreliminating residual reaction gas remaining on a wafer according to asecond embodiment of the present invention;

FIG. 4 is a schematic constructional view of a dry etcher foreliminating residual reaction gas remaining on a wafer according to athird embodiment of the present invention; and

FIG. 5 is a schematic constructional view of a dry etcher foreliminating residual reaction gas remaining on a wafer according to afourth embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Several preferred embodiments of the present invention will be describedin detail with reference to the accompanying drawings hereinafter, withlike elements being referred to by like reference numerals.

FIGS. 2 through 5 are four schematic constructional views of dry etchersfor eliminating residual reaction gas remaining on a wafer according tothe first through fourth embodiments of the present invention.

Referring to FIG. 2, the dry etcher includes an etching chamber 50 undera high degree of vacuum in which a wafer 20 is loaded by a carrier (notshown) and etched. A loadlock chamber 60 controls the etchingenvironment before and after the wafer is loaded in and unloaded fromthe etching chamber 50 by maintaining a high degree of vacuum nearlyequal to that in the etching chamber 50. A gas supplier 52 is connectedto the etching chamber 50 and supplies a reaction gas thereto such as,for example, Cl₂ or HBr.

A gas discharger 70, respectively connected to the etching chamber 50and the loadlock chamber 60, pumps/purges out the reaction gas in theloadlock chamber 60 and the etching chamber 50 after the etching processis completed, so as to maintain the high degree of vacuum in theloadlock chamber 60 and the etching chamber 50.

The dry etcher also includes a means for preventing any residualreaction gas remaining on the wafer from condensing. Specifically, aheater 80, such as an ultraviolet ray lamp or a halogen lamp, isdisposed in the loadlock chamber 60. The heater 80 heats the residualreaction gas remaining therein by means of light energy to therebyactivate the remaining gas so that the remaining gas on the wafer 20does not condense when exposed to the atmosphere.

In a second embodiment of the present invention as shown in FIG. 3, themeans for preventing any residual reaction gas remaining on the waferfrom condensing is an electric heater 81 that heats the residual gas inthe loadlock chamber 60 by electric energy instead of the light energyas in the first embodiment. In FIGS. 2 and 3, the remaining referencenumerals refer to the same or like parts.

In a third embodiment of the present invention as shown in FIG. 4, theheater 80, such as an ultraviolet rays lamp or a halogen lamp, isdisposed directly in the etching chamber 50 instead of the loadlockchamber 60 as in the first embodiment. The heater 80 heats any residualgas remaining in the etching chamber 50.

According to a fourth embodiment of the present invention as shown inFIG. 5, a cleaner 90 is disposed in the loadlock chamber 60 instead ofthe heaters 80 or 81 as set forth in the first and second embodiments.The cleaner 90 cleans the wafer 20 by means of deionized water.

In each of the various dry etcher embodiments of the present inventionas described above, the wafer 20 is carried by the carrier (not shown)and loaded in the etching chamber 50. Thereafter, the wafer 20 is etchedunder a high degree of vacuum by reacting with the reaction gas suppliedfrom the gas supplier 52 into the etching chamber 50.

Thereafter, the gas discharger 70 pumps/purges out the reaction gasremaining in the loadlock chamber 60 and the etching chamber 50 afterthe etching process. In this case, the heaters 80 or 81, disposed ineither the loadlock chamber 60 or the etching chamber 50, heat anyresidual gas remaining in the chambers to thereby activate molecularmovement of the gas. Likewise, this same result is achieved when thewafer 20 is cleaned by the cleaner 90 instead of being heated by theheaters 80 or 81. Therefore, the remaining gas does not condense on thewafer 20 even when the wafer 20 is exposed to the atmosphere afterexiting the loadlock chamber 60.

As described above, in the dry etcher according to the presentinvention, the remaining gas does not condense on the wafer when it isexposed to the atmosphere after the etching process. Therefore, the dryetcher according to the present invention does not require a separatedevice to eliminate the remaining gas, thereby improving the yield ofthe manufactured semiconductor devices.

Further, since the present invention does not require a separate deviceto eliminate the remaining gas, it is very effective in improving asemiconductor manufacturing system, in particular, a manufacturingsystem that employs multi-functional chambers. Multi-functional chambersare chambers whose functions are diversified as the wafers become largerand more highly integrated.

In the drawings and specification, there have been disclosed typicalpreferred embodiments of the invention and, although specific terms areemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation, it being understood that the scope of thepresent invention is set forth in the following claims and theirequivalents.

What is claimed is:
 1. A dry etcher for etching a thin film on a wafer,the dry etcher comprising:an etching chamber having the wafer loadedtherein; a supply means for supplying a reaction gas to said etchingchamber to etch the thin film on the wafer; a loadlock chamber forcontrolling an etching atmosphere before and after the wafer is loadedin and unloaded from the etching chamber; means for pumping the reactiongas, including any residual reaction gas remaining in the etchingchamber and the loadlock chamber, out of the etching chamber and theloadlock chamber after the thin film is etched; and means, disposed inthe loadlock chamber, for preventing the residual reaction gas remainingin the etching chamber and the loadlock chamber from being condensed onthe wafer when the wafer is exposed to ambient atmosphere after exitingthe loadlock chamber, wherein the means for preventing comprises acleaner for cleaning the wafer in the loadlock chamber, therebyeliminating the residual reaction gas from the wafer.
 2. A dry etcher asclaimed in claim 1, wherein the cleaner uses deionized water to cleanthe wafer.
 3. A dry etcher for etching a thin film on a wafer, the dryetcher comprising:an etching chamber having the wafer loaded therein; asupply means for supplying a reaction gas to said etching chamber toetch the thin film on the wafer; a loadlock chamber for controlling anetching atmosphere before and after the wafer is loaded in and unloadedfrom the etching chamber; means for pumping the reaction gas, includingany residual reaction gas remaining in the etching chamber and theloadlock chamber, out of the etching chamber and the loadlock chamberafter the thin film is etched; and means, disposed in the etchingchamber, for preventing the residual reaction gas remaining in theetching chamber and the loadlock chamber from being condensed on thewafer when the wafer is exposed to ambient atmosphere after exiting theloadlock chamber, wherein the means for preventing comprises a cleanerfor cleaning the wafer in the reaction chamber, thereby eliminating theresidual gas from the wafer.
 4. A dry etcher as claimed in claim 3,wherein the cleaner uses deionized water to clean the wafer.